Cache ID is the same as the JDBC connection URL of the registry database. This value is the Cache ID of the remote instance. It should be in the format of
$database_username is the username of the remote instance database and
$database_url is the remote instance database URL. This cacheID denotes the enabled cache. In this case, the database it should connect to is
REGISTRY_DB, which is the database shared across all the nodes. You can find that in the mounting configurations of the same datasource that is being used.